/*
 * base64-arraybuffer
 * https://github.com/niklasvh/base64-arraybuffer
 *
 * Copyright (c) 2012 Niklas von Hertzen
 * Licensed under the MIT license.
 */

var encode = function(arraybuffer) {
        var chars =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        var bytes = new Uint8Array(arraybuffer),
            i, len = bytes.length,
            base64 = "";

        for (i = 0; i < len; i += 3) {
            base64 += chars[bytes[i] >> 2];
            base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >>
                4)];
            base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i +
                2] >> 6)];
            base64 += chars[bytes[i + 2] & 63];
        }

        if ((len % 3) === 2) {
            base64 = base64.substring(0, base64.length - 1) + "=";
        } else if (len % 3 === 1) {
            base64 = base64.substring(0, base64.length - 2) + "==";
        }

        return base64;
    };

var decode = function(base64) {
        var chars =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        var bufferLength = base64.length * 0.75,
            len = base64.length,
            i, p = 0,
            encoded1, encoded2, encoded3, encoded4;

        if (base64[base64.length - 1] === "=") {
            bufferLength--;
            if (base64[base64.length - 2] === "=") {
                bufferLength--;
            }
        }

        var arraybuffer = new ArrayBuffer(bufferLength),
            bytes = new Uint8Array(arraybuffer);

        for (i = 0; i < len; i += 4) {
            encoded1 = chars.indexOf(base64[i]);
            encoded2 = chars.indexOf(base64[i + 1]);
            encoded3 = chars.indexOf(base64[i + 2]);
            encoded4 = chars.indexOf(base64[i + 3]);

            bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
            bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
            bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
        }

        return arraybuffer;
    };


module.exports = { encode : encode,
                   decode : decode };
